[OpenLayers-Dev] OpenLayers.Format.KML.write()
Tim Schaub
tschaub at openplans.org
Tue Sep 11 13:11:30 EDT 2007
Damien Corpataux wrote:
> Hi Tim,
>
> I just posted a patch on ticket #927. The patch suits the requirements:
> - KML extends XML
> - XML class methods are used for XML manipulation
> - tested on FF2/Linux and IE7
> - KML.write() returns a string (using XML.write())
> - GGE import of OL exported KML is working, and vice-versa
>
> My 2 cents
>
> Cheers,
> Damien
>
Thanks for the patch Damien. I rewrote things a bit and put this in
with r4219 [1]. I added support for KML MultiGeometry and improved the
read/write stuff so all OL geometries are supported. Also,
name/description attributes and feature id survive a round trip through
read/write.
There are likely still issues with the parser. In particular, we don't
write out feature attributes (beyond name/description).
You can play with the vector formats example to see OL KML output [2].
Paste in any KML you can find and report back any trouble with the parser.
Tim
[1] http://trac.openlayers.org/changeset/4219
[2] http://openlayers.org/dev/examples/vector-formats.html
>
> Tim Schaub wrote:
>> I've opened ticket #927 to track this.
>>
>> If anybody has a patch for KML, please attach it to that ticket.
>> Damien, I've referenced your email on the ticket.
>>
>> Since XML flavors should now all inherit from the XML format class, I'd
>> say that write will always return a string.
>>
>> Thanks for any contributions.
>> Tim
>>
>>
>> Damien Corpataux wrote:
>>
>>> Hello,
>>>
>>> As far as I can see, the advantages of doing so are obvious. Althought I
>>> didn't have time to apply these, here is a new version of the patch:
>>> - puts placemarks in a folder tag (for google earth import)
>>> - bugfix with geometry tags
>>>
>>> Is the question about write() return type (string or DOMDocuemt/DOMNode)
>>> still open?
>>>
>>> Cheers,
>>> Damien
>>>
>>>
>>> Patch:
>>> Index: /home/dcorpataux/workspace/openlayers/lib/OpenLayers/Format/KML.js
>>> ===================================================================
>>> ---
>>> /home/dcorpataux/workspace/openlayers/lib/OpenLayers/Format/KML.js
>>> (revision 3900)
>>> +++
>>> /home/dcorpataux/workspace/openlayers/lib/OpenLayers/Format/KML.js
>>> (working copy)
>>> @@ -8,8 +8,8 @@
>>> * @requires OpenLayers/Ajax.js
>>> *
>>> * Class: OpenLayers.Format.KML
>>> - * Read only KML. Largely Proof of Concept: does not support advanced
>>> Features,
>>> - * including Polygons. Create a new instance with the
>>> + * Read/write KML 2.0. Does not support advanced Features.
>>> + * Create a new instance with the
>>> * <OpenLayers.Format.KML> constructor.
>>> *
>>> * Inherits from:
>>> @@ -24,6 +24,24 @@
>>> kmlns: "http://earth.google.com/kml/2.0",
>>>
>>> /**
>>> + * APIProperty: placemarksDesc
>>> + * Default description for a placemark
>>> + */
>>> + placemarksDesc: "No description available",
>>> +
>>> + /**
>>> + * APIProperty: foldersName
>>> + * Default name for a folder
>>> + */
>>> + foldersName: "OpenLayers export",
>>> +
>>> + /**
>>> + * APIProperty: foldersDesc
>>> + * Default description for a folder
>>> + */
>>> + foldersDesc: "Exported on " + new Date(),
>>> +
>>> + /**
>>> * Constructor: OpenLayers.Format.KML
>>> * Create a new parser for KML
>>> *
>>> @@ -46,7 +64,7 @@
>>> if (typeof data == "string") {
>>> data = OpenLayers.parseXMLString(data);
>>> }
>>> - var featureNodes = OpenLayers.Ajax.getElementsByTagNameNS(data,
>>> this.kmlns, "", "Placemark");
>>> + var featureNodes = OpenLayers.Ajax.getElementsByTagNameNS(data,
>>> this.kmlns, "kml", "Placemark");
>>>
>>> var features = [];
>>>
>>> @@ -100,6 +118,19 @@
>>> // TBD Bounds only set for one of multiple geometries
>>> geom.extendBounds(p.bounds);
>>> }
>>> +
>>> + // match Polygon
>>> + } else if (OpenLayers.Ajax.getElementsByTagNameNS(xmlNode,
>>> + this.kmlns, "", "Polygon").length != 0) {
>>> + var polygon = OpenLayers.Ajax.getElementsByTagNameNS(xmlNode,
>>> + this.kmlns, "", "Polygon")[0];
>>> + p = this.parseCoords(polygon);
>>> + if (p.points) {
>>> + var linearRing = new
>>> OpenLayers.Geometry.LinearRing(p.points);
>>> + geom = new OpenLayers.Geometry.Polygon(linearRing);
>>> + // TBD Bounds only set for one of multiple geometries
>>> + geom.extendBounds(p.bounds);
>>> + }
>>> }
>>>
>>> feature.geometry = geom;
>>> @@ -191,5 +222,171 @@
>>> return p;
>>> },
>>>
>>> + /**
>>> + * Method: write
>>> + * Accept Feature Collection, and return an XML Document.
>>> + *
>>> + * Parameters:
>>> + * features - An array of <OpenLayers.Feature.Vector> features.
>>> + *
>>> + * Returns:
>>> + * <DOMDocument>
>>> + */
>>> + write: function(features) {
>>> + var kml = document.createElementNS(this.kmlns, "kml");
>>> + var folder = this.createFolderXML();
>>> + for (var i=0; i < features.length; i++) {
>>> + folder.appendChild(this.createPlacemarkXML(features[i]));
>>> + }
>>> + kml.appendChild(folder);
>>> + return kml;
>>> + },
>>> +
>>> + /**
>>> + * Method: createFolderXML
>>> + * Creates and returns a KML Folder node with default name and
>>> description
>>> + *
>>> + * Returns:
>>> + * xmlNode - {<XMLNode>}
>>> + */
>>> + createFolderXML: function() {
>>> + // Folder name
>>> + var folderName = document.createElementNS(this.kmlns, "name");
>>> + var folderNameText = document.createTextNode(this.foldersName);
>>> + folderName.appendChild(folderNameText);
>>> +
>>> + // Folder description
>>> + var folderDesc = document.createElementNS(this.kmlns,
>>> "description");
>>> + var folderDescText = document.createTextNode(this.foldersDesc);
>>> + folderDesc.appendChild(folderDescText);
>>> +
>>> + // Folder
>>> + var folder = document.createElementNS(this.kmlns, "Folder");
>>> + folder.appendChild(folderName);
>>> + folder.appendChild(folderDesc);
>>> +
>>> + return folder;
>>> + },
>>> +
>>> + /**
>>> + * Method: createPlacemarkXML
>>> + * Accept an OpenLayers.Feature.Vector, and create a KML Placemark node
>>> + *
>>> + * Parameters:
>>> + * feature - {<OpenLayers.Feature.Vector>}
>>> + *
>>> + * Returns:
>>> + * xmlNode - {<XMLNode>}
>>> + */
>>> + createPlacemarkXML: function(feature) {
>>> + // Placemark name
>>> + var placemarkName = document.createElementNS(this.kmlns, "name");
>>> + var placemarkNameText = document.createTextNode(feature.id);
>>> + placemarkName.appendChild(placemarkNameText);
>>> +
>>> + // Placemark description
>>> + var placemarkDesc = document.createElementNS(this.kmlns,
>>> "description");
>>> + var placemarkDescText =
>>> document.createTextNode(this.placemarksDesc);
>>> + placemarkDesc.appendChild(placemarkDescText);
>>> +
>>> + // Placemark
>>> + var placemarkNode = document.createElementNS(this.kmlns,
>>> "Placemark");
>>> + placemarkNode.appendChild(placemarkName);
>>> + placemarkNode.appendChild(placemarkDesc);
>>> +
>>> + // Geometry node (Point, LineString, etc. nodes)
>>> + var geometryNode = this.buildGeometryNode(feature.geometry);
>>> + placemarkNode.appendChild(geometryNode);
>>> +
>>> + return placemarkNode;
>>> + },
>>> +
>>> + /**
>>> + * Method: buildGeometryNode
>>> + * Builds a KML geometry node with a given geometry
>>> + *
>>> + * Parameters:
>>> + * geometry - {<OpenLayers.Geometry>}
>>> + *
>>> + * Returns:
>>> + * xmlNode - {<XMLNode>}
>>> + */
>>> + buildGeometryNode: function(geometry) {
>>> + // TBD test if geoserver can be given a Multi-geometry for a
>>> simple-geometry data store
>>> + // ie if multipolygon can be sent for a polygon feature type
>>> + var kml = "";
>>> + // match MultiPolygon or Polygon
>>> + if (geometry.CLASS_NAME == "OpenLayers.Geometry.MultiPolygon"
>>> + || geometry.CLASS_NAME == "OpenLayers.Geometry.Polygon") {
>>> + kml = document.createElementNS(this.kmlns, 'Polygon');
>>> +
>>> + var outerRing = document.createElementNS(this.kmlns,
>>> 'outerBoundaryIs');
>>> + var linearRing = document.createElementNS(this.kmlns,
>>> 'LinearRing');
>>> +
>>> + // TBD manage polygons with holes
>>> +
>>> linearRing.appendChild(this.buildCoordinatesNode(geometry.components[0]));
>>> + outerRing.appendChild(linearRing);
>>> +
>>> + kml.appendChild(outerRing);
>>> + }
>>> + // match MultiLineString or LineString
>>> + else if (geometry.CLASS_NAME ==
>>> "OpenLayers.Geometry.MultiLineString"
>>> + || geometry.CLASS_NAME ==
>>> "OpenLayers.Geometry.LineString") {
>>> + kml = document.createElementNS(this.kmlns,
>>> 'LineString');
>>> +
>>> + kml.appendChild(this.buildCoordinatesNode(geometry));
>>> + }
>>> + // match MultiPoint or Point
>>> + else if (geometry.CLASS_NAME == "OpenLayers.Geometry.Point" ||
>>> + geometry.CLASS_NAME ==
>>> "OpenLayers.Geometry.MultiPoint") {
>>> + kml = document.createElementNS(this.kmlns, 'Point');
>>> +
>>> + // FIXME: There should be only one Point node per
>>> Placemark node
>>> + var parts = "";
>>> + if (geometry.CLASS_NAME ==
>>> "OpenLayers.Geometry.MultiPoint") {
>>> + parts = geometry.components;
>>> + } else {
>>> + parts = [geometry];
>>> + }
>>> +
>>> + for (var i = 0; i < parts.length; i++) {
>>> + kml.appendChild(this.buildCoordinatesNode(parts[i]));
>>> + }
>>> + }
>>> + return kml;
>>> + },
>>> + /**
>>> + * Method: buildCoordinatesNode
>>> + * builds the KML coordinates node
>>> + *
>>> + * Parameters:
>>> + * geometry - {<OpenLayers.Geometry>}
>>> + *
>>> + * Returns:
>>> + * xmlNode - {<XMLNode>}
>>> + */
>>> + buildCoordinatesNode: function(geometry) {
>>> + var coordinatesNode = document.createElementNS(this.kmlns,
>>> "coordinates");
>>> +
>>> + var points = null;
>>> + if (geometry.components) {
>>> + points = geometry.components;
>>> + }
>>> +
>>> + var path = "";
>>> + if (points) {
>>> + for (var i = 0; i < points.length; i++) {
>>> + path += points[i].x + "," + points[i].y + " ";
>>> + }
>>> + } else {
>>> + path += geometry.x + "," + geometry.y + " ";
>>> + }
>>> +
>>> + var txtNode = document.createTextNode(path);
>>> + coordinatesNode.appendChild(txtNode);
>>> +
>>> + return coordinatesNode;
>>> + },
>>> +
>>> CLASS_NAME: "OpenLayers.Format.KML"
>>> });
>>>
>>>
>>> Tim Schaub wrote:
>>>
>>>> Hi-
>>>>
>>>> So, we're mid-way through changing how XML flavors are read/written in
>>>> OpenLayers.
>>>>
>>>> I've checked a new XML format in to the trunk. This format has most of
>>>> the methods we need for reading/writing XML cross-browser.
>>>>
>>>> To parse other XML flavors, format classes should be created that
>>>> inherit from the XML format.
>>>>
>>>> For an (incomplete) example, see:
>>>> http://dev.openlayers.org/sandbox/tschaub/xml/lib/OpenLayers/Format/GML.js
>>>>
>>>> (The important part to notice in the above example is that the GML
>>>> format inherits from the XML format.)
>>>>
>>>> Instead of using OpenLayers.Ajax methods or document methods, DOM
>>>> creation and traversal should be done with OpenLayers.Format.XML
>>>> methods. I've created methods to reflect the W3C standard XML DOM
>>>> methods - wrapping the standard ones and accommodating for non-compliant
>>>> browsers.
>>>>
>>>> If you (or anyone) needs additional XML DOM methods, they should be
>>>> added to the XML format. The next addition (in my mind) is
>>>> setAttributeNS. Aside from that, you should be able to do efficient
>>>> parsing and dom creation with the XML format methods.
>>>>
>>>> Please make modifications to the KML format in the trunk. Create a
>>>> ticket and attach patches in Trac. I can offer review or other help as
>>>> needed.
>>>>
>>>> I don't have time to keep these sandboxes entirely clean right now - so
>>>> please forgive anything you find that is in a half-developed state.
>>>>
>>>> Tim
>>>>
>>>> PS - Eventually, I'll move the following example into the trunk. It
>>>> would be nice if we could demonstrate read/write capability for all
>>>> vector formats in this way:
>>>> http://dev.openlayers.org/sandbox/tschaub/xml/examples/vector-formats.html
>>>>
>>>> (note again that this reflects partially complete work - and you should
>>>> not be surprised to encounter errors or see changes at any time)
>>>>
>>>>
>>>> Damien Corpataux wrote:
>>>>
>>>>
>>>>> Hello,
>>>>>
>>>>> Here's what I did so far... Reading KML only work for KML 2.0 namespaces
>>>>> for write() uses OpenLayers.Ajax.getElementsByTagNameNS(), but I'm
>>>>> pretty sure it will work on future versions (2.1 parsing successful).
>>>>> Also, GML and KML write() returns a Dom Document rather than a string.
>>>>> Should one change the result type, breaking OpenLayers.Format interface,
>>>>> or parse it into a string using OpenLayers.XML.....?
>>>>>
>>>>> Cheers,
>>>>> Damien
>>>>>
>>>>>
>>>>>
>>> [patch stripped]
>>>
>>> --
>>> Camptocamp SA
>>> Damien Corpataux
>>> PSE A
>>> CH-1015 Lausanne
>>> +41 21 619 10 22 (Direct)
>>> +41 21 619 10 10 (Centrale)
>>> +41 21 619 10 00 (Fax)
>>> P Please consider the environment
>>> Do you really need to print this email?
>>>
>>>
>>>
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>>
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>
>
> --
> Camptocamp SA
> Damien Corpataux
> PSE A
> CH-1015 Lausanne
> +41 21 619 10 22 (Direct)
> +41 21 619 10 10 (Centrale)
> +41 21 619 10 00 (Fax)
> P Please consider the environment
> Do you really need to print this email?
> !DSPAM:4033,46dd6bc8182553362379201!
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